PRIMARY ANORECTAL MELANOMA : REPORT OF A CASE

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1 Gastroenterol J Taiwan PRIMARY ANORECTAL MELANOMA : REPORT OF A CASE Department of Intemal Medicine', Buddhist Dalin Tzu Chi General Hospital, Chia-Yi, Taiwan Departments of Internal ~edicine', surgery2, ~adiology' and ~atholo~y', National Cheng Kung University Hospital, Tainan, Taiwan Department of ti tho log^', Chia-Yi Chnstian Hospital, Chia-Yi, Taiwan Primaly anorectal melanoma is a rare, but aggressively malignant tumor The most common manifestation is lower gastrointestinal bleeding. We report a case of a 70-year-old female with cirrhosis of liver who presented with hematochezia, and on Colonoscopy was found to have a brown-grayish promding anorectal mass that proven to be a melanoma. A series of imaging studies revealed no evidence of extra-luminal invasion, lymph node metastasis, and distant dissemination of tumor Thereafter; the tumor was removed by trans-anal excision. The patient remained well without any evidence of tumor recurrence during a 30-month follow-up. We suggest that primaly anorectal melanoma should be suspected in patients with concomitant presence of lower gastrointestinal bleeding and pigmented anorectal tumor In order to preserve qualily of life, and lessen operative morbid@, a conservative local excision might be a treatment option for primary anorectal melanoma, particularly in debilitatedpatients. Key words: amrectum, melanoma INTRODUCTION Primary anorectal melanoma is a rare but deadly tumor. It accounts for only 0.2% to 3% of all patients with malignant melanomas [I-31 and 0.1% to 4.6 % of all patients with anorectal malignant tumors [4-61. Reviewing the literature, there were 457 cases reported from 1857 to [7] and the first reported case was in 1857 [8]. The most common symptom of anorectal melanoma is lower gastrointestinal bleeding [I]. The correct diagnosis is often considered late, and symptoms are often present for several months before diagnosis. Surgical interventions either by local excision or by abdominoperineal resection are the treatment options for anorectal melanoma. The prognosis is dismal with a grave five-year survival rate of about 6% to 17% [1,4,7,9-131 and median overall survival period of 12 to 25 months [3,7,12,14]. We report a female patient of primary anorectal melanoma presented with hematochezia. Paitent received local excision and remained well without evidence of tumor recurrence during a 30-month post-operative follow-up. CASE REPORT A 70-year-old female patient with cirrhosis of liver presented with hematochezia. The same symptom had occurred about one year ago. However, she did not seek any medical aid until this episode of bleeding. On arrival, the physical examination disclosed pale conjunctiva, pulse rate of 11 7/min., and blood pressure Received: May 1,200 1 Accepted: December 28,200 1 Correspondence and reprint requests to: Dr. Pin-Nan Cheng, Division of Gastroenterology, Department of Internal Medicine, National Cheng Kung University Hospital, No. 138, Shing-Li Road, Tainan 704, Taiwan

2 Vol. 18. No Primary Anorectal Melanoma of 120/70 rnrnhg. The examinations of the chest, heart, and abdomen were unremarkable. No pigmented skin tumor was found. A mass with uneven surface and firm consistence was palpable by digital examination at 3 cm above the anal verge. Hetnatological studies revealed hemoglobin 9.4g/dL, platelet count 67 x ~O'IUL, and prolonged prothroinbin time that was 3.6 seconds longer than that of control. The serum biochemical tests showed mild elevation in total bilirubin level of 1.9 mg/dl (normal: mg/dl) and low albumin level of 2.6 g1dl (normal: 3-5 g/dl). Colonoscopy showed a brown-grayish protruding mass with irregular surface, approximately 3 cm in size and located at 3cm above the anal verge (Fig. 1). Pathological examination disclosed infiltrative nests among the lamina propria of anorectal mucosa, comprising large polygonal or spindle cells containing melanin pigments (Fig. 2A). Immunostain for anti-hmb-45 antibody revealed strong positivity (Fig. 2B). Lower gastrointestinal series revealed a 3 cm mass lesion at anorectal area (Fig. 3A). Abdominal and pelvic computed tomography showed an anorectal mass, but without any paraaortic, iliac or inguinal lymph node involvement (Fig. 3B). Thereafter, patient received trans-anal wide excision under the preoperative diagnosis of stage I anorectal melanoma. The excised specimen showed a 3x5 cm pigmented mass with firm consistence (Fig. 2C), and the tumor cells were involved into submucosal layer, but the mangin was free. The post-operative course was uneventful. Patient remained well without any evidence of tumor recurrence during a 30-month outpatient follow-up. DISCUSSION Primary anorectal melanoma is a rare but malignant tumor that is usually detected late. The average duration before diagnosis is 5 months [I]. It accounts for approximately % of all melanomas [l-31 and % of anorectal malignant tumors [4-61. The anorectal region is the third most common primary site of melanoma and is also the most fiequent Fig. 1. C'olonoscopy suvsaled an irregular prottuding mass \\ ~ th bson n-gr-ny~sh pigmentation, 3 cni in size and located 3cm above the anal \ urge.

3 K. C. Tseng, P. N. Cheng, et al. Gastroenterol J Taiwan Fig. 2A. The histology of biopsy specimen showed Fig. 2B. Immunostain for anti-hmb-45 antibody infiltrative nests among the lamina propria of revealed intensive cytoplasmic positivity anorectal mucosa with evident melanin (DAB as chromogen, X 200). pigmentation (H&E stain, X 200). Fig. 2C. Grossly. the excised specimen showed brownish pigmentation with irregular surface.

4 Vol. 18, No. 4,2001 Primary Anorectal Melanoma Fig. 3A. Lower gastrointestinal series showed a mass lesion at anorectal area (arrow). Fig. 3B. Computed tomography of abdomen and pelvis showed an anorectal mass (mow), but without any paraaortic. iliac or inguinal lymph node involvement. site of gastrointestinal melanoma. Anorectal melanoma occurs predominantly in females, with increasing incidence particularly in the older age group [I -4, The most common symp'tom of anorectal melanoma is lower gastrointestinal bleeding that is sometimes misdiagnosed as hemorrhoid. Other presentations include pelvic mass, abdominal pain, and obstipation [I]. The diagnosis of anorectal melanoma is based on physical examination. colonoscopy and pathological examination. The typical endoscopic finding is black pi-mentation in a nodule with ulceration and friability [I 7,181. However, one-third of melanomas are amelanotic [15]. Because of abundant vascular supply and lymphatic drainage, regional invasion (stage 11) or distal metastasis (stage 111) frequently occur during presentation and account for approximately one-fifth to two-thirds of patients [1,3,4,12,14,15]. They are i~sually manifested by a large pelvic mass, diffuse bilateral pulmonary nodules, or diffuse liver metastasis [14]. Therefore, once the diagnosis is made, image studies including chest X-ray and computed

5 K. C. Tseng, P. N. Cheng, et al. tomography of abdomen and pelvis are required for staging. Since anorectal melanoma is not responsive to radiotherapy, and the role of chemotherapy and imrnunotherapy remains unclear, surgical resection is the choice of treatment in the majority of cases [19]. The methods of surgical treatment include local excision and abdominoperineal resection with or without lymphadenectomy [3, There are extensive controversies regarding which type of surgical procedures should be performed. Abdominoperineal resection does not seem to offer any significant difference in the survival time, but it does have some effect in controlling the local recurrence as well as in extending the disease-free period [ 121. However, in order to minimize the associated operative or post-operative morbidity and preserve the quality of life, local excision might be the preferred choice for initial treatment, particularly in debilitated patients. In contrast, abdominoperineal resection should be reserved for those patients with bulky local disease that cannot be removed by local excision alone and for salvage control in selected patients with local recurrence [12]. In our case, the patient received trans-anal mass excision without lymphadenectomy. Such surgical treatment seemed to be good enough to maintain her quality of life without any complications resulting fiom the surgery or tumor itself. Primary anorectal melanoma is a rare disease in Taiwan, and a rare cause of lower gastrointestinal bleeding. It should be suspected in patients presented with hematochezia and pigmented anorectal tumors during colonoscopic examination. In order to preserve the quality of life for debilitated patients, local excision might be the choice of treatment for primary anorectal metanoma. REFERENCES 1. Wanebo HJ, Woodruff JM, Farr GH, et al. Anorectal melanoma. Cancer ;7: Mills SE, Cooper PH. Malignant melanoma of the digestive system. Path01 Annu. 1983; 18: Goldman S, Glimelius B, Pahlman L. Anomcal malignant melanoma in Sweden. Dis colon Rectum 1990;33: Weinstock MA. Epidemiology and prognosis of anorectal melanoma. Gastroenterology 1993: 104: Longo WE, Vernava AM III, Wade TP, et al. Rare anal canal cancers in the U.S. veteran: patterns of disease and results of treatment. Am Surg 1995;6 1 : Klas JV, Rothenberger DA, Wong WD, et al. Malignant tumors of the anal canal: the spectrum of disease, treatment, and outcomes. Cancer 1999;85: Bolivar JC, Harris JW, Branch W, et al. Melanoma of the anorectal region. SurgGynecol Obstet 1982; 154: Moore W. Recurrent melanoma of the rectum after previous removal fiom the verge of the anus in a man aged sixty-five. Lancet 1857; 1 : Siegal B, Cohen D, Jacob ET. Surgical treatment of anorectal melanoma. Am J Surg 1983; 146: Ward MWN, Romano G, Nicholls RJ. The surgical treatment of anorectal malignant melanoma. Br J Surg 1986;73: Angeras U, Jonsson N, Jonsson P. Primary anorectal malignant melanoma. J Surg Oncol 1983;22: Ross M, Pezzi C, Pezzi T, et al. Patterns of failure in anorectal melanoma. Arch Surg 1990; 125: Brady MS, Kavolius JP, Quan SHQ. Anorectal melanoma: a 64-year experience at Memorial Sloan-Kettering Cancer Center. Dis Colon Rectum 1995; 38: Slingluff CL, Vollmer RT, Seigler HF. no rectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery 1990;107: Cooper PH, Mills SE, Allen MS. Malignant melanoma of the anus: report of 12 patients and analysis of additional cases. Dis Colon Rectum 1982;25:

6 Vol. 18, No. 4,2001 Primary Anorectal Melanoma 16. Kantarovsky A, Kaufman 2, Zager M, et al. 18. Gupta R, Rathi PM, Sawant P, et al. Endoscopic Anorectal region malignant melanoma. J Surg appearance of primary anorectal melanoma. Oncol 1988;38: Endoscopy 1997;29: Rubin KP, Ghanekar D, Friedrich A, et al. 19. Eng J, Sabanathan S, Whittaker M. Primary Endoscopic diagnosis of anorectal melanoma. anorectal malignant melanoma. Acta Chir Scand N J Med 1992;89: ; 155: